-- Discussion containing changed information from previous version are highlighted. --
282
FXUS62 KILM 130542
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
142 AM EDT Mon May 13 2024

.SYNOPSIS...
Mostly dry weather continues through Monday. High rain chances
arrive for Tuesday through Wednesday with an approaching storm
system. Dry weather and weak high pressure returns for Thursday
and Thursday night before rain chances return for Friday and
beyond with the next storm system.

&&

.NEAR TERM /THROUGH TODAY/...
High pressure settles overhead this evening bringing calm winds
and clear skies. Weak return flow pushes inland early this
evening as NW winds relax. This additional surface moisture
advection could lead to a better chance of ground fog along the
Grand Strand overnight. Radiational cooling overnight will bring
temperatures in the low 50s with a few of our typical cold
spots dropping into the upper 40s. Swamps and low lying areas
could see patchy ground fog inland as well.

High pressure slides offshore throughout the day and
southeasterly winds become reestablished across the region. An
ejecting shortwave to our south and west will bring increasing
upper level cloud cover. Increased low level moisture advection
will bring an afternoon cumulus deck and within this deck, some
afternoon showers will develop across the southern Pee Dee
through early evening. Showers will be light initially with the
best lift and heaviest precip arriving after sunset. Highs in
the lower 80s due to clouds and onshore flow.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
The approach of a closed low from the central plains states
will send multiple shortwaves across the area during this
period, which should combine with increasing deep-layer moisture
to produce considerable rainfall totals by Wednesday morning,
particularly near the coast. With surface high pressure offshore
at the start of the period, increasing moisture aloft and
isentropic ascent over a warm front will yield
lowering/thickening clouds and perhaps some scattered light
showers during Monday night. As better forcing for ascent
arrives attendant to a lead shortwave in tandem with anomalous
pwats exceeding 1.75" (reaching or exceeding the 99th percentile
for this time of year), more widespread rain is expected to
overspread the region on Tuesday morning. With increasing
elevated instability as the warm front nears, convective
elements may enhance rainfall rates, leading to locally heavy
rainfall until the warm front lifts through, which is progged to
occur during the afternoon. Although the probability is low due
to showers and abundant cloud cover through most or all of the
daylight hours, a marginal risk for severe weather is outlooked
for most of our SC zones on Tuesday as there will be plenty of
wind shear available, but the limiting factor will be whether
much surface-based destabilization can occur.

With another shortwave hot on the heels of the first one,
expect showers and at least isolated thunderstorms to continue
affecting the area from Tuesday evening into the night without
much of a break in between. However, as this second shortwave
passes overhead and a surface cold front slides through from the
west, expect shower coverage to decrease considerably during
the latter half of Tuesday night.

Temperatures will be limited by thick cloud cover and shower
activity with advection primarily driving temperature changes.
Morning lows on Tuesday should fall into the middle 60s before
rebounding into the mid-upper 70s, warmest south. With only weak
cool advection arriving on WSWrly low-level flow behind the cold
front, morning lows on Wednesday should end up in the mid-upper
60s, mostly depending on how low dewpoints go behind the front.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
With the cold core associated with the closed mid-level low
tracking overhead on Wednesday, lapse rates will steepen and
should help to yield weak to moderate instability during the
afternoon, given enough surface heating occurs. With 30-40 kts
of effective shear in play and up to around 1000 J/kg of DCAPE
shown in forecast soundings, the severe weather risk is
certainly not zero. The key question is whether any organized
convection will come to fruition as multiple impulses rotating
about the low will likely yield scattered to perhaps widespread
shower activity, thereby keeping surface-based instability low.
Even if organized convection does not occur, showers may contain
gusty winds and small hail as wet-bulb zero heights fall
throughout the day. Highs should reach the middle 80s assuming
the cold core remains just far enough north to prevent
widespread cloudiness.

A second cold front is expected to drop southward as the mid-
level low and its associated surface reflection move offshore
over Wednesday night. Ridging quickly builds in and dry weather
ensues for Thursday and Thursday night before another collection
of shortwaves and vorticity impulses bring wet weather for the
weekend, although confidence in the timing and evolution of
these shortwaves is rather low at this time. Thus, PoPs for
Friday afternoon through Saturday are largely held in the 40-50%
range for now. Of course, temperatures will depend on the final
outcome of these shortwaves, but overall highs are expected to
reach the low-mid 80s from Thursday onward with morning lows in
the middle 60s, both of which are slightly above-normal.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
VFR conditions continue. For the next few hours there is the
threat for some MVFR BR but high clouds seem to be slowing down
the process for now. The attention then turns to late tonight
when the impacts from a broad storm system begin to be felt.
For now ceilings and visibilities look to remain VFR but will
have begun their slow deterioration.

Extended Outlook...Flight restrictions may occur Monday night
into Tuesday with the next weather system moving in. Improving
conditions into Thursday. Another system approaches the area for
next weekend.
-- End Changed Discussion --

&&

.MARINE...
Through Monday...High pressure overhead this evening will
gradually push offshore overnight. Light and variable winds will
become SE tomorrow morning. Winds increase to 10-15 knots
during the afternoon ahead of an ejecting shortwave from the
Southeastern US. Showers will develop ahead of this disturbance
late tomorrow afternoon, primarily in the SC nearshore waters.
Showers and storms move northward into tomorrow evening. Seas
1-2 feet.

Monday night through Friday...A complex low pressure system
will send a warm front through on Tuesday with SSE flow turning
to SSW behind it during the day. Seas rapidly increase from 2 ft
early in the period to 6+ ft around midday Tuesday with wind
gusts also peaking around 25 kts. Thus, SCA conditions are
expected from midday Tuesday through Tuesday night with
conditions subsiding below SCA criteria around midday Wednesday.
A cold frontal passage early on Wednesday will veer winds to
WSWrly with gusts possibly scraping 25 kts and seas hovering
around 4-5 ft during the afternoon, so while an SCA is not
likely by definition, conditions will be close to criteria. A
second cold front is expected to drop in from the north on
Wednesday night into Thursday morning with winds veering to
northwesterly and subsiding through the day while seas fall to
around 2-3 ft. Weak high pressure briefly takes control for
Thursday night into Friday, with variable flow at or below 10
kts ending up at southeasterly ahead of the next system poised
to affect the area over the weekend.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
NC...Coastal Flood Advisory until 4 AM EDT early this morning for
     NCZ107.
SC...None.
MARINE...None.
-- End Changed Discussion --

&&

$$

SYNOPSIS...ILM
NEAR TERM...21
SHORT TERM...ABW
LONG TERM...ABW
AVIATION...SHK
MARINE...21/ABW